Solderless method for transferring high frequency, radio frequency signals between printed circuit boards

ABSTRACT

A connector system and method for cooperating printed circuit boards includes a housing member having a clip receiving slot and circuit board engaging surface that is positioned against a first printed circuit board. At least one electrically conductive clip member has opposing ends and is received within the clip receiving slot. One end is readily secured by soldering to a circuit on the first printed circuit board and the other end is biased into connection with the circuit of a second printed circuit board such that high frequency radio frequency signals are transferred from one printed circuit board to the other printed circuit board via the clip member.

RELATED APPLICATION

[0001] This application is based upon prior filed copending provisionalapplication Serial No. 60/318,732 filed Sep. 11, 2001.

FIELD OF THE INVENTION

[0002] This invention relates to the field of connectors for printedcircuit boards and similar applications, and more particularly, thisinvention relates to the transfer of high frequency, radio frequencysignals between cooperating printed circuit boards.

BACKGROUND OF THE INVENTION

[0003] Traditionally, high frequency radio frequency signals greaterthan about 500 MHz require subminiature coaxial connectors (SMA) thatwork in conjunction with connected coaxial cables for transferringsignals between printed circuit boards or other components. Althoughthese subminiature coaxial connectors are semi-precision, subminiaturedevices used with coaxial cables, including flexible and semi-rigidcabling, the types of connections required to make high frequency signaltransfer adequate are relatively large and expensive.

[0004] Subminiature coaxial connectors operate at broadband frequenciesand have low reflections. Many are designed to have a constant 50 Ohmimpedance, making them advantageous for use in various applications inthe microwave industry. Many different types of SMA connectors areavailable, but these connectors are large and expensive to use in somedesigns.

[0005] Some surface mount, pressure contact connectors have beendesigned for use in traditional DC signal connections, but usually neverfor transferring high frequency radio frequency signals (up to 4 GHz ormore). Although some connectors have been used for transferring one ofeither DC signals or high frequency signals, such as disclosed in U.S.Pat. No. 5,188,534; 5,129,832; 5,595,490; and 5,991,165, adequateconnection methods have not been known that allow the mixing of highfrequency and DC signals on the same surface mount contact connectorwithout impacting performance. It is also desirable if high frequencysignals could be transferred with a solderless connection through a lowcost, surface mount, spring or similar contact, while also allowingtransfer of some DC signals. Additionally, many prior art connectorsrequire solder connections at both ends, making assembly of the circuitboards and other component assemblies more difficult.

SUMMARY OF THE INVENTION

[0006] It is therefore an object of the present invention to provide asurface mount, pressure contact connector system that allows mixing ofhigh frequency and DC signals without impacting performance.

[0007] It is another object of the present invention to provide aconnector system between cooperating circuit boards that allows highfrequency signals to be transferred with a solderless connection througha low cost, surface mount, spring or similar contact.

[0008] The present invention provides a connection method for connectinga pair of cooperating printed circuit boards and allowing highfrequency, radio frequency signal transfer in a solderless connection toa second printed circuit board. It also permits DC signal transfer.

[0009] In accordance with the present invention, a housing member has aclip receiving slot and a circuit board engaging surface that ispositioned against a first printed circuit board. At least oneelectrically conductive clip member that acts as a spring-like pin hasopposing ends and is received within the clip receiving slot. One end ofthe clip member is readily secured by soldering to a circuit on thefirst printed circuit board. Another end of the clip member is biasedinto connection with a circuit of a second printed circuit board suchthat high frequency radio frequency signals are transferred from oneprinted circuit board to the other printed circuit board via the clipmember.

[0010] In yet another aspect of the present invention, the connectorsystem includes a plurality of housing members positioned adjacent toeach other such that respective electrically conductive clip members arereceived within the housing members and positioned for interconnectingradio frequency signal lines, ground lines and DC signal lines that areformed on first and second printed circuit boards.

[0011] In yet another aspect of the present invention, the housingmember is formed from plastic and is substantially rectangularconfigured. It includes a flat circuit board engaging surface that restsagainst the first circuit board. The electrically conductive clip memberis substantially v-shaped and has a first leg member and an end thatengages a circuit or trace on the first circuit board member. A secondleg member includes an end that is spring biased against a circuit ortrace on the second circuit board member. The end of the second legmember includes a bent contact forming a radius (concave) surface to aidin engaging a circuit on the second board member. The housing memberincludes a shoulder formed within each clip receiving slot that engagesthe second leg member to maintain a biasing force not only against theshoulder, but against the second circuit board to which it engages.

[0012] In yet another aspect of the present invention, a plurality ofelectrically conductive clip members that act as spring-like pins haveopposing ends and are received within respective clip receiving slots.One end is readily secured by soldering to the circuit on the firstprinted circuit board and the other end is biased in connection with acircuit of a second printed circuit board. A clip member interconnects aradio frequency signal line and adjacent clip members interconnectground lines and DC signal lines for transferring high frequencysignals, ground connections and DC signals from one printed circuitboard to the other printed circuit board via the clip members.

[0013] A method is also disclosed for connecting a pair of cooperatingprinted circuit boards and comprises the step of soldering to a circuitof a first printed circuit board an end of at least one electricallyconductive clip member that is received within a clip receiving slot ofa housing member having a circuit board engaging surface that restsagainst the first printed circuit board. The other end of theelectrically conductive clip member is biased against the circuit of thesecond printed circuit board.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Other objects, features and advantages of the present inventionwill become apparent from the detailed description of the inventionwhich follows, when considered in light of the accompanying drawings inwhich:

[0015]FIG. 1 is a fragmentary, sectional view of a surface mount,pressure contact connector of the present invention and showing aconnection between a first and second printed circuit board.

[0016]FIG. 2 is an isometric view illustrating a number of connectorspositioned adjacent to each other on a first printed circuit board forforming a connection system of the present invention, where highfrequency radio frequency signals, ground and DC signals are transferredbetween overlying, cooperating circuit boards.

[0017]FIG. 3 is a graph showing the measured results for transferringradio frequency signals up to 3 GHz using the connector system shown inFIGS. 1 and 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The present invention will now be described more fullyhereinafter with reference to the accompanying drawings, in whichpreferred embodiments of the invention are shown. This invention may,however, be embodied in many different forms and should not be construedas limited to the embodiments set forth herein. Rather, theseembodiments are provided so that this disclosure will be thorough andcomplete, and will fully convey the scope of the invention to thoseskilled in the art. Like numbers refer to like elements throughout.

[0019] The present invention advantageously uses a connection methodwhich, in one aspect of the present invention, is a surface mount,pressure contact connector that transfers high frequency, radiofrequency signals (up to 4 GHz or more) with very low losses. It alsoallows the mixing of high frequency and DC signals on the same surfacemount, pressure contact connector without impacting performance. Highfrequency signals can be transferred with a solderless connectionthrough a low cost, surface mount spring-type contact of the presentinvention.

[0020]FIG. 1 illustrates a portion of a surface mount, pressure contactconnector 10 of the present invention that allows solderless connectionbetween circuit boards. Some prior art connectors that act asspring-type pin or chip contacts have been used at low cost in theindustry to transfer DC signals between stacked layers of printedcircuit boards (PCB). For example, one type of DC connector has beenused in cellular telephones. The present invention goes beyond DC signaltransfer, and is an improvement over standard DC connectors because itallows high frequency, radio frequency signals to be transferred with asurface mount, pressure contact application.

[0021] As shown in the fragmentary, partial sectional view of FIG. 1,the connector 10 connects a pair of cooperating first and second printedcircuit boards 12, 14, i.e., a first and second printed circuit board.The connector 10 includes a housing member 16 having a clip receivingslot 18 (also referred to as a pin receiving slot) and a circuit boardengaging surface 20 that is positioned against the first printed circuitboard 12. In one aspect of the present invention, each housing member 16includes three clip receiving slots 18 as illustrated in FIG. 2, wherethree housing members 16 are shown adjacent to each other. The housingmember 16 is preferably formed from plastic and is substantiallyrectangular configured and includes a substantially flat, circuit boardengaging surface that rests prone against the flat surface of theprinted circuit board. Each clip receiving slot 18 is formed as arectangular cut-out and includes a shoulder 22 for engaging theelectrically conductive clip members 24 as shown in FIG. 1.

[0022] Each clip member 24 is substantially v-shaped as shown in FIG. 1.The clip members 24 are small and can also be referred to as pinsbecause of their small, spring-like and pin-like capacity to make “pin”connections. Each clip member 24 includes a first leg member 30 and endthat engages the first printed circuit board 12. This end includes adrop down shoulder 30 a that is soldered to a circuit trace or othercircuit on the first printed circuit board 12. The upper portion of thefirst leg member 30 is received within the clip receiving slot 18. Asecond leg member 32 has an end that is spring biased against the secondprinted circuit board 14. The second leg member 32 includes a bentcontact end 32 a that forms what could be referred to as a “pin” orspring contact for engaging in a biased condition a circuit or trace onthe second circuit board member. The leg member 32 engages the shoulder22 in the clip receiving slot to maintain a biasing force or“spring-action” of the clip member against the shoulder, while alsomaintaining a biasing force against the second printed circuit boardsuch that the pressure contact established by the bent end of the secondleg member engages the circuit, trace or other connection point on thesecond printed circuit board. The second (or first) printed circuitboard can have metallized pads that align with the connector “pins”formed by the clip member 24.

[0023] In one aspect of the invention where a number of connectors 10form a connection system 38 as shown in FIG. 2 (the top or secondprinted circuit board is shown removed), a central clip memberinterconnects a radio frequency signal line 40 as a preferred 50 ohmimpedance radio frequency signal line, known to those skilled in theart. Adjacent clip members 24 (or pins) interconnect ground lines 42positioned on the opposing side of the radio frequency signal line 40.Although only one ground pin per side shown, the number of ground pinscan be varied to increase isolation and improve return loss. Otheradjacent clip members 24 (pins) connect DC and signal lines 44. Thus,the connector system 38 using the connectors 10 of the present inventioncan transfer not only high frequency signals, but also groundconnections and DC signals from one printed circuit board 12 to theother printed circuit board 14 via the clip members forming thespring-like pin connections.

[0024] In one aspect of the present invention, the spacing between theclip members (or pins) is about 40 mils and DC signals could be carriedon other clip members in the same connector.

[0025]FIG. 3 is a chart illustrating the measured results fortransferring radio frequency signals up to 3 GHz using the contactconnectors shown in FIG. 2. The insertion loss at 3 GHz is about 0.5 dBand the return loss is approximately −14 dB. Other measurements showthat this connector works reliably up to 4 GHz with less than 1 dBinsertion loss and less than 10 dB return loss.

[0026] Many modifications and other embodiments of the invention willcome to the mind of one skilled in the art having the benefit of theteachings presented in the foregoing descriptions and the associateddrawings. Therefore, it is to be understood that the invention is not tobe limited to the specific embodiments disclosed, and that themodifications and embodiments are intended to be included within thescope of the dependent claims.

That which is claimed is:
 1. A method for connecting a pair ofcooperating printed circuit boards comprising: positioning a housingmember having a clip receiving slot and a circuit board engaging surfaceagainst a first printed circuit board, wherein at least one electricallyconductive clip member having opposing ends is received within the clipreceiving slot; and soldering an end of the clip member to a circuit onthe first printed circuit board and biasing another end into connectionwith a circuit of a second printed circuit board such that highfrequency radio frequency signals are transferred from one printedcircuit board to the other printed circuit board via the clip member. 2.A method according to claim 1, and further comprising the step ofpositioning a plurality of housing members adjacent to each other suchthat respective electrically conductive clip members received withinsaid housing members are positioned for interconnecting radio frequencysignal line, ground lines, and DC signal lines that are formed on firstand second printed circuit boards.
 3. A method according to claim 1, andfurther comprising the step of forming the at least one housing memberfrom plastic.
 4. A method according to claim 1, and further comprisingthe step of forming the at least one housing member as a substantiallyrectangular configured housing member having a substantially flatcircuit board engaging surface.
 5. A method according to claim 1, andfurther comprising the step of forming each electrically conductive clipmember as substantially v-shaped having a first leg member and an endthat engages the first circuit board member and a second leg memberhaving an end that is spring biased against the second circuit boardmember.
 6. A method according to claim 5, and further comprising thestep of forming the end of said second leg member as a bent contact endto aid in engaging a circuit on the second circuit board member.
 7. Amethod according to claim 5, and further comprising the step of formingthe housing member as a shoulder within each clip receiving slot thatengages the second leg member to maintain a biasing force.
 8. Aconnector system for connecting a pair of cooperating printed circuitboards, including the transfer of DC and high frequency signalscomprising: at least one housing member having a circuit board engagingsurface that is positioned against a first printed circuit board and aplurality of substantially parallel clip receiving slots formed therein;a plurality of electrically conductive clip members having opposing endsand received within respective clip receiving slots and having one endthat is readily secured by soldering to a circuit on the first printedcircuit board and another end that is biased into connection with acircuit of a second printed circuit board wherein a clip memberinterconnects a radio frequency signal line and adjacent clip membersinterconnect ground lines and DC signal lines for transferring highfrequency signals, ground connections and DC signals from one printedcircuit board to the other printed circuit board via the clip members.9. A connector system according to claim 8, and further comprising aplurality of housing members positioned adjacent to each other such thatrespective electrically conductive clip members received within saidhousing members are positioned for interconnecting the respective radiofrequency signal line, ground lines, and DC signal lines.
 10. Aconnector system according to claim 8, wherein said at least one housingmember is formed from plastic.
 11. A connector system according to claim8, wherein said at least one housing member comprises a substantiallyrectangular configured housing member having a substantially flatcircuit board engaging surface.
 12. A connector system according toclaim 8, wherein each electrically conductive clip member issubstantially v-shaped having a first leg member and an end that engagesthe first circuit board member and a second leg member having an endthat is spring biased against the second circuit board member.
 13. Aconnector system according to claim 8, wherein said end of said secondleg member comprises a bent contact end to aid in engaging a circuit onthe second circuit board member.
 14. A connector system for connecting apair of cooperating printed circuit boards, including the transfer of DCand high frequency signals comprising: at least one housing memberhaving a circuit board engaging surface that is positioned against afirst printed circuit board and a plurality of substantially parallelclip receiving slots formed therein, each substantially parallel clipreceiving slots including a shoulder; a plurality of electricallyconductive clip members having opposing ends and received withinrespective clip receiving slots and having one end that is readilysecured by soldering to a circuit on the first printed circuit board andanother end that engages said shoulder such that said end engaging theshoulder against the shoulder and biased into connection with a circuitof a second printed circuit board wherein a clip member interconnects aradio frequency signal line and adjacent clip members interconnectground lines and DC signal lines for transferring high frequencysignals, ground connections and DC signals from one printed circuitboard to the other printed circuit board via the clip members.
 15. Aconnector system according to claim 14, and further comprising aplurality of housing members positioned adjacent to each other such thatrespective electrically conductive clip members received within saidhousing members are positioned for interconnecting the respective radiofrequency signal line, ground lines, and DC signal lines.
 16. Aconnector system according to claim 14, wherein said at least onehousing member is formed from plastic.
 17. A connector system accordingto claim 14, wherein said at least one housing member comprises asubstantially rectangular configured housing member having asubstantially flat circuit board engaging surface.
 18. A connectorsystem according to claim 14, wherein each electrically conductive clipmember is substantially v-shaped having a first leg member and an endthat engages the first circuit board member and a second leg member andan end that is spring biased against the second circuit board member.19. A connector system according to claim 18, wherein said end of saidsecond leg member comprises a bent contact end to aid in engaging acircuit on the second circuit board member.
 20. A method of connecting apair of cooperating printed circuit boards comprising the steps of:soldering to a circuit of a first printed circuit board an end of atleast one electrically conductive clip member that is received within aclip receiving slot of a housing member having a circuit board engagingsurface that rests against the first printed circuit board; and biasingthe other end of the electrically conductive clip member against acircuit of a second printed circuit board.